My 1995 2ltr TD has a preheat time of about 1 second. Seems very short to me.
Is this right, what's yours?
Thanks in anticipation. Zeb.

Hi There,
Mine is usually at least 4 seconds in my TD Spacewagon. Sounds like something is acting up!
Cheers
M

Thanks Salamander, at last someone has posted me a reply, I owe you a Guiness!
4 seconds sounds much more sensible, it is not a problem at the moment but might be in the winter I reckon.
Once or twice recently it's started on just one or two cylinders for a couple of seconds, so I might have a glowplug or two gone, I wonder if this would cause the preheat time to be shortened?
I intend to call in at a Mit. agent sometime & ask.
I reckon I will have to measure them individually, but that means taking off the intercooler so it's not a 5 min. job.
My garage suggested feeling how hot they got after the preheat (without starting), but with only a second or so don't think this would work, so I might power them directly from the battery for a few seconds & then feel them?
Still thinking about the best way to proceed.

Yeah, this is a pretty slow forum alright. I guess spacewagon and rvr owners are not the most technically minded! ;)

Do you have a multimeter? Cos you could try to measure the resistance of all four plugs. You may not have to remove the intercooler if you can reach the glow plug bar with one probe. If more than two are busted then the result should be out of spec according to the figures in the workshop manual i have.

Ive been trying to figure out how the preheat timing works on these machines. It seems there are two different types of glow system and two different resisances for each system.
1 Super quick heating system. 0.05-0.07ohm @20C (68F)
2 Self regulating glow system. 0.1-0.15ohm @20C (68F)

The only way i can figure out which is what is that the super quick heating system has two relays mounted on a bracket on top of the front right suspension mount. The Self regulating has just one as is the case for my spacewagon.

If you get a reading of double the above figures or more then its safe to say theres one or two plugs gone. For testing the plug individually the reading should be 4 times the above figures if the plug is good. A bad plug should have a very high resistance.

I reckon any busted glow plugs might shorten the preheat time, due to an increase in resistance which would make the system think the plugs were hotter than they actually are.
But there is aparrently another factor as well. A faulty coolant temp sensor might let the system think the engine is hotter than it really is. Try disconnecting it and try again to see it's at fault. Though you'll probably have to remove the intercooler to get at that as it is located beside one of the injectors.

Hope I haven't confused you too much. I can barely get through it myself. I'll have to go tinkering tomorrow. If you want I could send you the manual on pdf. You might be able to make more sense of it than I can at the moment.

Bye for now,
M

PS about that guinness, could you post it over :laughing:

Thanks very much Salamander (M), great post.
Mine is the same as yours, with the single relay.
I have measured the resistance of the glowplug bus, and its 0.112 ohms, so thats got to be right for the "self regulating" system. (Fed in 1.5 amps from a constant current source & measured the voltage drop).
BTW, the power take off for this circiut is direct from the battery via a 80A fuse labelled (in english!) "glowplug". Presumably for the super quick system this would have to be bigger?
There are two sensors in the manifold by the bus, one is a single terminal one, and the other has two wires going to it.
Was able to remove the wire to the single terminal one, and it's o/c, so did'nt try starting the car with the wire off, as it can't have made a difference.
Is this the one for the glowplugs?
If so, then perhaps it's supposed to be s/c when cold, going o/c when hot (ie normal thermostat working), and so if the ECU sees o/c it thinks the engine is hot & shortens the preheat time?
When you start yours when hot, is the time much shorter?, if so, this would prove the theory.
Thanks for the offer of the manual, is it the pukka Mit. one or the USA "Expo" one that you can get via eBay?
I got this Expo one, but it came with a "mitchell repair install disk", which you have to install on your PC in order to read the Expo disk itself, as its encrypted. However, as I don't have a PC I have not been able to use it.
If we can't sort out the prob. between us then perhaps I could have the manual in due course?
Thanks for your interest, much appreciated, Zeb.

Hi
I'm going on holidays tomorrow so I've atttached the engine electrical manual that I have been getting my figures from. Its 1.1Mb so it shouldn't take too long to download.

Aye the light goes off quicker as the engine heats up. If the temp needle goes above approx 1/4 it won't come on at all. Today I started it in the afternoon and it went out quicker than usual about 2 sec. Might have been something to do with the warm weather as i usually start her in the morning when it would be colder.

From the manual it seems the resistance of the sensor changes as the engine heats up. There is a controller which must sense the amount of current passing through the sensor. At 0C its 8.6k ohms and at 20C it 3.25k ohms. Quite a big difference. So maybe if the car has been in the sun for the day the dash light may not stay on as long?

There are another few things to check which are outlined in the manual such as relays etc. It kind of takes a little figuring out.

Just read through your first thread and a thought has just struck me! Was it definetly running on two cylinders? I sometimes noticed my engine starting poorly in the mornings. But after looking at the fuel pump one day i noticed that before you start the engine when its cold and you press the accelerator once it reset the cold idle speed. This brought the revs up from about 600 rpm to about 1500 rpm and it started first time every time. Just a thought. Sometimes the simplest answers are best ones (even if thay are a bit frustrating when you've just taken your engine to bits :) )

Anyway, I hope I have been of some help to you. Got to go. Let us know how you get on. Will be back on Monday. Enjoy the weekend!
Bye M

Oh I forgot to ask,
What sort of MPG do you get from your machine. I think mine is quite high at 35-40mpg. I mostly do drives at 50-60mph for 1/2 hour or more.
Thanks
M.

Thanks Salamander (M). I too am away this w/e so wont get to progress further.
Thanks for the manual, will take it with me for study.
Had not heard of depressing the throttle before starting, will try it. I have the NZ manual, will see if it's mentioned in there.
Have only done 800 miles since I bought it, an am only getting 30mpg, but it's an auto. I drive as steadily as I can, so don't think I can improve on this.
Thanks again for your help.

Update. Measured/timed the glowplug voltage yesterday. The dashboard light only stays on for 1 sec, but the plugs heat for about 7, ie for 6 seconds after the lamp goes out. (initially I was assuming the they were timed together, but the diagram on p. 16.30 clearly shows the difference). BTW I reckon pages 16.28 to 16.32 refer to the "self. reg. system)
My temp. sensor measured ok, and disconnecting it did'nt make any difference to these times.
So T1 is about 1 sec; T2 about 7 sec.
From the same diagram it appears that "afterglow" (T3) is only powered if the engine is started, and the time of this is determined by the temp. sensed. Don't think the temp sensed changes T2.
So I reckon mine must be ok, although I have not checked that T3 power is applied.